The present invention relates to cases for accommodating tape cassettes.
An example of tape cassettes is a tape cassette 101 for digital videorecorder as shown in FIG. 7. The tape cassette 101 comprises a magnetic tape 102, a pair of reels 103, 104 having the magnetic tape 102 wound thereon, a shell 105 for rotatably accommodating the tape reels 103, 104, a pair of tape guides 107, 108 for running the magnetic tape 102 withdrawn from the tape reels 103, 104 in a pocket 106 arranged in the shell 105, and a reel lock member 109 for unrotatably locking the tape reels 103, 104.
Referring to FIG. 8, when loading the tape cassette 101 in a videotape recorder (VTR), locking of the tape reels 103, 104 by the reel lock member 109 is released, and the magnetic tape 102 is withdrawn from the pocket 106 through movable tape guides 201 and stationary tape guides 202 of VTR and is wound on a rotary head 203 of VTR. Referring to FIG. 9, the tape reels 103, 104 are raised by a pair of reel supports 204 of VTR to be in non-contact with a lower half 105b of the shell 105, i.e. in the rotatable state. And the magnetic tape 102 is run by the tape reel 103, 104 to record/reproduce the magnetic tape 102 through the rotary head 203 of VTR.
Referring to FIG. 10, when unloading the magnetic tape 102 after completion of its recording/reproducing operation, the movable tape guides 201 of VTR are returned to the pocket 106 of the tape cassette 101, and the magnetic tape 102 is wound on the tape guides 107 by a predetermined angle. Then, the tape reels 103, 104 are locked by the reel lock member 109. Subsequently, referring to FIG. 11, the reel supports 204 are separated from the tape reels 103, 104 which are moved downward to have lower flanges 103b, 104b contacting the lower half 105b of the shell 105, closing reel-support openings 110 formed in the lower half 105b.
When the tape reels 103, 104 are locked by the reel lock member 109 as described above, a tension is applied to the magnetic tape 102 which is thus pressed on the tape guides 107, 108. Moreover, due to a friction produced between the magnetic tape 102 and the tape guides 107, 108, the magnetic tape 102 sticks on the tape guides 107, 108. In that state, if the tape reels 103, 104 are moved downward, the magnetic tape 102 is inclined as shown in FIG. 11 to have an upper edge 102a pressed on upper flanges 103a, 104a of the tape reels 103, 104, suffering damage.
It is confirmed that damage of the magnetic tape 102 is not produced by applying no tension thereto when the tape reels 103, 104 are locked by the reel lock member 109. With the reel lock member 109 which applies no tension to the magnetic tape 102, however, when the magnetic tape 102 undergoes a great impact, which occurs, e.g. when dropping the tape cassette 101, it is bent greatly to disenable its normal loading in VTR, resulting in possible occurrence of a bite, etc.
If the tape cassette 101, which is accommodated in a tape-cassette case with the magnetic tape 102 inclined and with the upper edge 102a contacting the upper flanges 103a, 104a of the tape reels 103, 104, is kept during a long period of time in a general environment with 24.degree. C. temperature and 45% humidity which are determined in view of an average environment in Japan, or during a short period of time in a worse environment with higher temperature and humidity, the upper edge 102a of the magnetic tape 102 pressed on the upper flanges 103a, 104a is deformed to cause a characteristic deterioration of the magnetic tape 102 such as off tracking or defective contact.
Referring to FIG. 12, a plastic tape-cassette case 301 is proposed to solve such inconvenience of the tape cassette 101. The tape-cassette case 301 includes a pair of reel supports 303, 304 on a bottom 302a of a cassette compartment 302. With the tape-cassette case 301, the tape cassette 101 inserted in the cassette compartment 302 has the shell 105 supported on the bottom 302a thereof, and the tape reels 103, 104 raised by the reel supports 303, 304 at a predetermined height H apart from the lower half 105b of the shell 105, preventing a deformation of the magnetic tape 102. This height H is substantially equal to the height obtained when the tape reels 103, 104 are supported by the reel supports 204 of VTR.
With the known tape-cassette case 301, however, the lower half 105b of the shell 105 of the tape cassette 101 is supported by the bottom 302a of the cassette compartment 302, so that referring to FIG. 13, if the bottom 302a has a bend .delta. the tape reels 103, 104 cannot be raised by the reel supports 303, 304 at the predetermined height H apart from the lower half 105b of the shell 105. An insufficient raise of the tape reels 103, 104 results in a deformation of the magnetic tape 102.
It is, therefore, an object of the present invention to provide cases for accommodating tape cassettes, which are free from a deformation of magnetic tapes.